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Professor Simon Meagher and Professor Ritsuko Pooh Performing Ultrasound Examinations Using the Voluson E22 System
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Congenital heart disease is among the most common congenital abnormalities in fetuses; however, prenatal detection remains challenging in routine obstetric practice. Although professional organizations such as ISUOG have issued detailed guidelines on the fetal cardiac ultrasound views that should be assessed, missed diagnoses still occur, mainly due to suboptimal image quality and inconsistent application of fundamental technical principles.
What is the DAZE technique?
In a recent study published in Ultrasound in Obstetrics & Gynecology, the journal of ISUOG, Dr. Perez and colleagues introduced the DAZE technique (Depth, Angle, Zoom, Enhancement) – a systematic, easy-to-apply, and reproducible approach designed to optimize 2D ultrasound imaging as well as color Doppler in fetal cardiac assessment.
DAZE does not replace guidelines for fetal cardiac anatomical views. Instead, it serves as a standardized process to help the operator optimize image quality before assessing cardiac structure and function.
Why is optimizing fetal cardiac ultrasound imaging important?
The fetal heart is a small structure that moves continuously at a high frequency and has complex anatomy. Image quality depends not only on the experience of the ultrasound operator but also closely on the adjustment of technical parameters on the ultrasound system.
Suboptimal imaging may reduce spatial resolution and temporal resolution, making it more difficult to identify small anatomical structures or abnormal blood flow on color Doppler. This directly affects the ability to detect fetal cardiac abnormalities, particularly complex congenital heart defects.
The DAZE technique was developed to standardize the image optimization process, enabling ultrasound operators to approach the examination in a more logical, sequential, and effective manner.
D – Depth: Adjusting depth and focal zone position
The first step of the DAZE technique is to optimize Depth and the focal zone. An excessively large depth setting causes the examination field to include unnecessary tissue, which can reduce frame rate and affect temporal resolution. Conversely, an excessively shallow depth may prevent the entire cardiac structure from being adequately visualized.
According to the DAZE principles:
- The fetal heart should occupy a large portion of the screen while still allowing all relevant structures to be fully visualized.
- The focal zone should be positioned at the level of the heart or the region of interest to optimize lateral resolution.
- Adjustments should be made according to gestational age, fetal position, and the specific anatomical view being assessed.
This is the foundational step for improving image quality from the beginning of the examination.
A – Angle: Optimizing scan angle and angle of insonation
“Angle” in the DAZE technique includes two important factors:
1. Angle Width
Reducing the scan angle width helps focus ultrasound energy on the region of interest, thereby increasing frame rate and improving temporal resolution. This is particularly important when assessing small structures such as heart valves, the interventricular septum, great vessels, and blood flow on color Doppler.
2. Angle of Insonation
The direction of the ultrasound beam has a significant impact on image quality and the assessment of blood flow. In color Doppler, an appropriate examination angle helps display blood flow more clearly, reduce artifacts, and improve sensitivity for detecting hemodynamic abnormalities.
Z – Zoom: Appropriate image magnification
“Zoom” is the step that enhances visualization of small anatomical details. However, magnification is not simply a matter of making the image larger. The DAZE approach emphasizes the appropriate use of zoom when assessing standard fetal cardiac views, allowing clearer visualization of the heart valves, cardiac septa, and great vessels.
E – Enhancement: Enhancing system settings
The final step of the DAZE technique is Enhancement – optimizing the settings of the ultrasound system. Parameters that may require adjustment include Gain, Dynamic range, Persistence, Speckle reduction, Harmonic imaging, Color Doppler settings, Pulse Repetition Frequency (PRF), and Wall filter.
For color Doppler, optimizing PRF, gain, and the color box is particularly important when evaluating blood flow across the heart valves, through the great vessels, and identifying abnormal flow patterns.
The role of modern ultrasound technology
The study by Dr. Perez and colleagues used illustrative images and videos acquired using the Voluson ultrasound system from GE HealthCare.
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Voluson Ultrasound System
With the ability to provide high-resolution imaging, optimize color Doppler, and support a range of advanced processing tools, modern ultrasound platforms play an important role in improving the quality of fetal cardiac assessment, particularly in the detection of congenital abnormalities.
As the need for prenatal diagnosis continues to grow, combining anatomical knowledge, practical scanning skills, and structured approaches such as DAZE may help improve screening effectiveness, support more accurate diagnosis, and provide practical benefits for both pregnant women and their fetuses.
Reference: https://obgyn.onlinelibrary.wiley.com/doi/10.1002/uog.70282
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